1. Field of the Invention
Exemplary embodiments of the invention relate to a backlight unit and a liquid crystal display using the same.
2. Discussion of the Related Art
A range of application for liquid crystal displays has gradually widened because of its excellent characteristics such as light weight, thin profile, and low power consumption. The liquid crystal displays have been used in personal computers such as notebook PCs, office automation equipments, audio/video equipments, interior/outdoor advertising display devices, and the like. A backlit liquid crystal display occupying most of the liquid crystal displays controls an electric field applied to a liquid crystal layer and modulates light coming from a backlight unit, thereby displaying an image.
The backlight unit is classified into a direct type backlight unit and an edge type backlight unit. In the direct type backlight unit, a plurality of light sources are positioned on a lower surface of a diffusion plate, and thus light travels to a back surface of a liquid crystal display panel. On the other hand, the edge type backlight unit includes a plurality of light sources positioned opposite the side of a light guide plate and a plurality of optical sheets between the liquid crystal display panel and the light guide plate. In the edge type backlight unit, the light guide plate converts line light or point light coming from the light sources into planar light, and the optical sheets allow the planar light to travel to the back surface of the liquid crystal display panel.
More specifically, the edge type backlight unit includes a cover bottom, the plurality of light sources that are positioned at one side of the cover bottom and provide light, the light guide plate that is positioned under the liquid crystal display panel so as to guide light from the light sources to the liquid crystal display panel, a reflection sheet for reflecting light reflected under the light guide plate to the front of the light guide plate, the plurality of optical sheets that are stacked on the light guide plate and provide uniform light to the liquid crystal display panel, and a guide panel for supporting the liquid crystal display panel.
In the related art, a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), etc. were used as the light source of the backlight unit. However, a light emitting diode (LED) has been recently spotlighted because it can be driven at a low voltage and has excellent characteristics such as low power consumption, an excellent color reproduction characteristic, an excellent contrast ratio, and a long life span.
As shown in FIG. 1, when the LED is generally used as the light source in the related art, a plurality of LEDs 1 are mounted on a light source printed circuit board (PCB) 2 to constitute an LED array. The LED array is fastened to the side of a bottom cover 4 with a heat sink 3 interposed between the LED array and the bottom cover 4. A connector 5 is fastened to one side of the light source PCB 2 and thus is used to apply a driving power supplied through a wire 6 to the LEDs 1. The wire 6 is electrically connected to a light source driver (not shown) via a through hole 7 formed in a bottom surface of the bottom cover 4.
In the related art backlight unit, because the connector 5 is positioned inside a liquid crystal module including the liquid crystal display panel and the backlight unit, the wire 6 is fastened to the connector 5 in an initial assembly stage (i.e., before the reflection sheet, the light guide plate, etc. are assembled) of the backlight unit and then has to be drawn out through the through hole 7. The backlight unit may include the plurality of connectors 5 based on its type. As a result, in the related art, when the wire 6 is drawn out, an assembly performance may be reduced because it is difficult to arrange the wire 6. This increases the assembly cost.
Further, in the related art, because the wire 6 is fastened to the connector 5 in the initial assembly stage of the backlight unit, it is impossible for a user to confirm whether or not the wire 6 is well fastened to the connector 5 with his or her eyes after the assembly of the liquid crystal module is completed.
Further, in the related art, because a bezel width BZ of the liquid crystal display is forced to increase by an area of the light source PCB 2 the connector 5 occupies, it is difficult to achieve a narrow bezel technology.